This invention relates to an escalator apparatus and, more particularly, to an escalator apparatus in which a plurality of segment-shaped steps are disposed along a circular, sloped, endless loop defining a circulating path having an upper load bearing run, a lower return run, and turn-around portions.
FIGS. 16 to 20 illustrate one example of a conventional circular escalator disclosed in Japanese Patent Publication No. 62-33196. In these figures, reference numeral 1 indicates a main frame defining thereon a circulating travel path along which a plurality of steps 3 are conveyed, 2 indicates a step loop having a plurality of steps connected into an endless loop, the step loop 2 having an upper load-bearing run, a lower return run, a lower end, a turn-around portion 2a and an upper end turn-around portion 2a'. The turn-around portions 2a and 2a' are disposed in lower and an upper horizontal portions 2b and 2b', respectively, and the load-bearing run and the return run are sloped to extend between the lower and the upper horizontal portions 2b and 2b' and curved in plan along an arc having a constant radius of curvature R as illustrated in FIG. 17.
In order to drive the steps 3 thus constructed, a rack 4a secured to a rack mount 4 is mounted to the opposite ends of the step 3, and a pinion gear 5 in mesh with the rack 4a is provided.
Further, the interconnection between each of the steps 3 is achieved by the application of a two-link speed changing mechanism as illustrated in FIGS. 19 and 20. That is, the two-link speed changing mechanism is composed of a first roller 7 rotatably mounted to the step 3 and guided by a first guide rail 6 for guiding the step 3, a second roller 9 guided by a second guide rail 8 for changing and maintaining predetermined intervals and predetermined level differences between the steps, and links 10 connecting the above rollers 7 and 9. With this construction, it is possible to drive the steps 3 or the step loop 2 smoothly with the inner and the outer sides of the steps 3 moved along a constant radius of curvature as viewed in a horizontal projection. Reference numeral 11 indicates a rail supporting rolling rollers 12 rotatably mounted to the step 3, 3a indicates the tread of the step 3, and 3b indicates a riser defined by a conical surface and disposed on the rear end of the step 3. The riser 3b and the tread 3a have formed thereon a plurality of cleats.
Another example of a conventional circular escalator which is disclosed in Japanese Patent Publication No. 62-33197 is illustrated in FIGS. 21 to 24. In these figures, the conveyer circulating path 1 on the main frame is arranged so that the radius of curvature on a horizontal plane varies in accordance with the variation of the slope angle.
FIG. 21 is an enlarged plan view of one part of FIG. 16, FIG. 22 is a side view of FIG. 21 and FIG. 23 is a sectional view of FIG. 21. In these figures, reference numerals 13 and 14 respectively indicate a first and a second outer guide rail disposed radially outside of the circulating path 1, 15 and 16 respectively indicate a first and a second inner guide rail disposed radially inside of the circulating path 1, and reference numeral 17 indicates a guide rail disposed along the center of the circulating path 1.
Reference numeral 18 indicates a step axle disposed at one end portion of the step 3 extending in the widthwise direction of the step 3 for supporting the step 3, the step axle 18 having at its opposite end portions a pair of main rollers 19 for rolling along the first outer guide rail 13 and the first inner guide 15, respectively. Reference numeral 20 indicates a pair of follower rollers disposed at both sides of the other end of step 3, the follower rollers 20 rolling along the second outer guide rail 14 and the second inner guide rail 16.
Reference numeral 21 indicates a shoe disposed on the center of the backside of the step 3. The shoe 3 is in contact with the guide rail 17 to prevent the swinging motion of the step 3.
Also, as best shown in FIG. 23, the step axle 18 is generally sloped so that the outer main roller 19 is positioned at a higher level than the inner main roller 19 in the load-bearing run, and the outer and the inner rails 13 and 15 are correspondingly positioned, whereby each of the steps 3 is maintained in a horizontal position by the rollers 19 and 20 in the load-bearing run and the return run.
Reference numeral 22 indicates an outer chain connected to each step axle 18 rotatably in a verticla and a horizontal direction at the radially outside portion of the steps 3, and 23 indicates an inner chain connected to each step axle 18 at the radially inside portion of the steps 3 similarly to the outer chain 22.
Further, FIG. 24 is a side view illustrating a turn-around portion of the steps 3 illustrated in FIG. 16, in which reference numeral 24 indicates a drive unit, 25 indicates an outer gear meshing with the outer chain 22, 26 indicates an inner gear meshing with the inner chain 23, and each of gears 25 and 26 is connected to the drive unit 24 through a drive chain 27.
In the conventional escalator constructed as described above, the drive force of the drive unit 24 is transmitted to the outer and inner gears 25 and 26 through the drive chain 27 to rotate each of the gears 25 and 26. This causes the outer and the inner chains 22 and 23 meshing with the gears 25 and 26 to be moved to drive the steps 3. At this time, each step 3 is limited as to the distance between the neighboring step 3 by each of the chains 22 and 23.
On the other hand, each of the chains 22 and 23 receives the drive force for driving the steps 3 and limiting the distance between the steps 3, thereby bearing the loads of the steps 3 and passengers thereon positioned at a level lower than the chains. Therefore, each of the chains 22 and 23 is subjected to elongations due to the loads.
As a counter measure for this, the position of the chains 25 and 26 is made changeable, particularly at the lower turn-around portion, in the direction of elongation of the chains 22 and 23 (in the right-hand direction in FIG. 24), so each of the chains 22 and 23 is in mesh with the gears 25 and 26 even when some elongation occurs in the chains 22 and 23.
Since the conventioanl apparatus is constructed as above, in the first example, it is necessary to provide a first guide rail 6 and a second guide rail 8 for guiding the first roller 7 and the second roller 9, respectively, and the configuration and the dimensions of the guide rails 6 and 8 must be highly precise to produce the necessary differential between the inner and outer side speeds of the steps 3. Therefore, the mechanism is complicated and must be highly precise, making its manufacture difficult and costly and making the reliability of the system low because of the above complexity.
In the second example of the conventional escalator apparatus, the amount of elongation of each of the chains 21 and 22 is not uniform and, particularly in a curved or circular escalator apparatus, the amounts of elongation of the outer chain and the inner chain are often different, the difference between the elongations of the outer and the inner chains becomes large as the chain elongation becomes large, and the meshing conditions between the gears 25 and 26 and the chains 21 and 22 at the lower turn-around portion is degraded, often resulting in undesirable states in the driving of the steps 3. Also, since the chains 21 and 22 serve not only to transmit drive force to the steps 3 but also to limit the distance between the steps 3, the elongation of the chains 21 and 22 causes the gap between the steps 3 to disadvantageously increase.